in a large sauce pan bring 4 cups of water to a boil. drop in the soba noodles, and boil for 4-5 mins. strain in the sink under cold water until the noodles are cold. place the noodles in a bowl and pour the soba sauce over the noodles. add the kimchi on top of the noodles, add the natto on top of the kimchi. sprinkle the scallion and sesame seeds over the top and serve.